CHAR-TARGET-002: Photo-z Calibration Fields

Parent requirement

R-CAL-B-NP-5100

R-CAL-B-NP-5200

R-CAL-B-NP-5300

R-CAL-B-NP-5400

Objective

The purpose of these observations is to obtain NISP-P photometry in YJH bands for a sample of 20,000 galaxies with existing visible and near-infrared ground-based spectroscopy. The S/N must be 5 times better than that of the wide survey. Based on the spectroscopic reference data, the Euclid photo-z methods can be calibrated.

VIS data are needed to perform the target detection and selection in an identical manner as in the wide survey, and to help with deblending. This significantly improves the photometric redshifts. In addition, OU-MER needs VIS data to provide consistent catalogs. The minimum depth for VIS is 2x the wide survey depth. For practial and legacy purposes, all observations are conducted with the ROS, so VIS will also go to 5x the survey depth.

Cadence

Observations

Methodology / Uplink procedure

Targets and pointing constraints

Table 15: Photo-z calibration fields. N_ROS refers to the number of times the ROS needs to be repeated for each pointing to reach the desired S/N, compensating for extinction and background. N_ROS is determined by EC-SURV and not imposed by calibration. CSV file

# ID	R.A.	Dec	Geometry	N_ROS	Time
COSMOS-wide	150.119	+02.21	2x2	75	358.3 h
VVDS-Deep	36.500	-04.50	1x1	58	69.3 h
CDFS	53.117	-27.81	1x1	34	40.6 h
SXDS	34.500	-05.00	2x2	58	277.1 h

Instrument configuration

Inter-operability constraints

Dependencies

Fulfilling

Fulfilled by

CALBLOCK-F-005: Photo-z Calibration Fields

Time-critical

There is a trade-off between depth and area, both of which are important to have early on in the mission. The 2x2 COSMOS field must be started in the first year, and completed in the following fashion:

1. Observe 50% of the area to 3x the depth

2. Observe the same 50% to 5x the depth

3. Repeat steps 1 and 2 for the remaining 50% of the area, ideally still within the first year.

At least one of the other fields shall be completed in each of the following years (starting with the second year). The 2x2 SXDS has the same completion strategy as COSMOS.

COSMOS and CDFS have priority in the first two years, since these data also fulfil CALBLOCK-F-004: Color Gradient Calibration Fields.

Validation

Recovery

In-orbit duration

Processing time

Processing input

Ground Processing Input Data:

Data Description:

Data volume

2761824 MB (624 executions of the ROS)

Processing tools

Processing element

DataModel: https://gitlab.euclid-sgs.uk/

Quality control parameters

DataModel: https://gitlab.euclid-sgs.uk/

Required accuracy, constraints

Must reach 5 times the average S/N of the wide survey.

Processing method

Processing output

Updated photo-z procedures

Contact person

Calibration Lead

Status

2026/09/18 - In progress.

FLAG

Priority

Observation record

Comments